JP2004263969A - Pyrolytic gasification melting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pyrolytic gasification melting system for minimizing the quantity of auxiliary fuel to be used and eliminating melting damage of a refractory material in a gasification furnace, a melting furnace and a pyrolytic gas passage for connecting the both furnaces and passage block-up of the pyrolytic gas passage. <P>SOLUTION: This pyrolytic gasification melting system pyrolyzes general garbage and industrial waste by a pyrolytic gasification furnace 3, and burns pyrolyric gas and char generated by the pyrolytic gasification furnace 3 by the melting furnace 6, and melts ash in the char by providing a high temperature field. An auxiliary fuel supply system is arranged for supplying the auxiliary fuel (f and g) to the pyrolytic gas passage 5 for flowing the pyrolytic gas and the char by connecting the pyrolytic gasification furnace 3 and the melting furnace 6. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention pyrolyzes general refuse and industrial waste in a pyrolysis gasifier, burns the pyrolysis gas and char generated in the gasifier in a melting furnace, obtains a high temperature field, and obtains ash in the char. The present invention relates to a pyrolysis gasification and melting system for melting gas.
[0002]
[Prior art]
A conventional pyrolysis gasification and melting system for treating general waste and industrial waste will be described with reference to FIG. In the figure, 1 is a feed hopper, 2 is a dust feeder, 3 is a fluidized bed gasifier, 4 is a diffuser pipe, 5 is a pyrolysis gas flow path, 6 is a melting furnace, 7 is a secondary combustion chamber, and 8 is A waste heat boiler, 9 is a temperature reducing device, 10 is a dust collector, 11 is a chimney, a is fluidized air, b is combustion air, c is slag, d is fly ash, and e is auxiliary fuel.
[0003]
The refuse and waste as fuel are supplied to the fluidized-bed gasifier 3 and pyrolyzed and gasified in a state of insufficient air, and the generated pyrolysis gas and char mainly composed of unburned carbon and ash are melted in the melting furnace. By burning in step 6, a high temperature field is obtained to convert the ash in the char into molten slag. In this process, garbage and waste are reduced in volume, and dioxins are completely decomposed and detoxified at high temperatures.
[0004]
In the pyrolysis gasification and melting system, when the amount of waste is small or when the calories burned are low, the auxiliary fuel e and the combustion air b are supplied to the melting furnace 6 to melt the ash in the melting furnace 6. It must be kept above the temperature. In most cases, liquid fuel such as kerosene or heavy oil, which has a low fuel cost, is used. However, the volume of the melting furnace 6 is reduced to reduce the heat radiation loss from the melting furnace 6.
[0005]
Therefore, the time required for evaporating the liquid fuel and completing the combustion may not be sufficient, and the fuel may be post-burned at the outlet of the melting furnace 6 or at the secondary fuel chamber 7 which is a downstream device. Therefore, the injected fuel e cannot be efficiently burned in the melting furnace 6, and not all of the heat input is converted into heat, so that an excessive amount of the fuel e is injected into the melting furnace 6, resulting in a high fuel cost. is there.
[0006]
Further, since the auxiliary fuel e has a calorie several times higher than the pyrolysis gas obtained by pyrolyzing general waste and industrial waste, when a flame is formed in the melting furnace 6, a region where the temperature is locally high is formed, There is a problem that the refractory material of the melting furnace 6 is melted and damaged.
[0007]
These problems are solved by supplying an auxiliary fuel to the gasification furnace side as disclosed in Patent Document 1 below. However, since a region having a high oxygen concentration exists locally in the gasifier, when the auxiliary fuel is supplied to the gasifier as described above, the auxiliary fuel supplied to the region having a high oxygen concentration burns. As a result, a locally high temperature region is formed. Thus, the gasification furnace in which a refractory material having a heat-resistant temperature lower than that of the melting furnace has a high degree of erosion of the refractory material.
[0008]
The region where the oxygen concentration is locally high in the gasification furnace is, for example, a region into which leaked air from a dust supply system or a sand circulation system flows, or a region where secondary air is supplied in a furnace of a type that supplies secondary air. Pointed out area.
[0009]
In addition, depending on the location of the auxiliary fuel e, a high-temperature region is formed at the gasification passage outlet portion where the flow passage is narrow, and the molten ash adheres to the portion and solidifies to form a clinker. Therefore, special consideration must be given to the supply of auxiliary fuel to the gasification furnace.
[0010]
[Patent Document 1]
JP-A-9-236220
[Problems to be solved by the invention]
As described above, when the auxiliary fuel is supplied to the melting furnace, the temperature cannot be increased efficiently, the fuel cost increases due to an increase in the amount of auxiliary fuel, and the problem of erosion of the refractory material due to the local formation of a high-temperature region. There is. On the other hand, also in the case of supplying the auxiliary fuel to the gasifier, there is a problem that the refractory material is melted due to the local formation of a high-temperature region.
[0012]
An object of the present invention is to solve such disadvantages of the prior art, and to solve the problem of erosion of refractory material in a gasification furnace, a melting furnace and a pyrolysis gas flow path connecting the two, and obstruction of the flow path in the pyrolysis gas flow path. An object of the present invention is to provide a pyrolysis gasification / melting system that can solve the problem and reduce the amount of auxiliary fuel by minimizing the amount of auxiliary fuel used.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a first means of the present invention is to thermally decompose general waste, industrial waste, and the like in a pyrolysis gasifier, and to decompose the pyrolysis gas and char generated in the pyrolysis gasifier. In a pyrolysis gasification and melting system that burns in a melting furnace to obtain a high temperature field and melts the ash in the char, pyrolysis in which the pyrolysis gas and the char flow by connecting the pyrolysis gasification furnace and the melting furnace An auxiliary fuel supply system for supplying auxiliary fuel to the gas flow path is provided.
[0014]
According to a second aspect of the present invention, in the pyrolysis gasification and melting system, an auxiliary fuel supply system that supplies auxiliary fuel to a low oxygen concentration region near an upper portion or an outlet of the pyrolysis gasification furnace is provided. It is a feature.
[0015]
According to a third aspect of the present invention, in the first or second aspect, the auxiliary fuel is a liquid fuel such as kerosene or heavy oil or a gaseous fuel such as propane gas or natural gas. It is.
[0016]
According to a fourth aspect of the present invention, in the third aspect, when the pyrolysis gas flowing in the pyrolysis gas channel or near the upper portion or the outlet of the pyrolysis gasification furnace exceeds the softening temperature of ash, Liquid fuel is supplied, and when the pyrolysis gas is at or below the softening temperature of ash, gaseous fuel is supplied.
[0017]
The fourth means of the present invention is the method according to the third means or the fourth means, wherein the liquid fuel is finely divided into fine particles of the pyrolysis gas flow path or an upper portion of the pyrolysis gasification furnace or in the vicinity of an outlet portion. It is characterized by supplying.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment in which the present invention is applied to a pyrolysis gasification and melting system for general waste disposal will be described with reference to FIG.
[0019]
In the figure, 1 is a feed hopper, 2 is a dust feeder, 3 is a fluidized bed gasifier, 4 is a diffuser pipe, 5 is a pyrolysis gas flow path, 6 is a melting furnace, 7 is a secondary combustion chamber, and 8 is Waste heat boiler, 9 is a temperature reducing device, 10 is a dust collector, 11 is a chimney, 12 is a temperature measuring device, 13 is a control device, a is fluidized air, b is combustion air, c is slag, and d is flying. Ash, f is liquid fuel, g is gaseous fuel.
[0020]
The present system is a combination of a fluidized-bed gasification furnace 3 and a whirl-type melting furnace 6, and a secondary combustion chamber 7 is provided downstream of the melting furnace 6 for complete combustion of exhaust gas. The apparatus further includes a waste heat boiler 8 for recovering heat from exhaust gas, an exhaust gas temperature reducing device 9 for suppressing resynthesis of dioxins, and a dust collecting device 10 as a dust collecting device.
[0021]
The refuse is supplied to the fluidized bed gasifier 3 by the dust supply device 2 and fluidized together with a fluid medium such as sand by the fluidizing air a supplied from the diffuser 4 installed at the bottom of the gasifier 3. . During this process, the refuse is partially burned and pyrolyzed to generate pyrolysis gas and char mainly composed of unburned carbon and ash. The generated pyrolysis gas and char are sent to the swirling melting furnace 6, where they react with the separately supplied combustion air b and burn. The inside of the melting furnace 6 is maintained at a temperature higher than the melting temperature of the ash, and the ash in the char is melted and collected as slag.
[0022]
In this system, when the low-calorie refuse is treated, the temperature of the melting furnace 6 is lower than the melting temperature of the ash, so the auxiliary fuel is supplied to the pyrolysis gas flow path 5 connecting the gasification furnace 3 and the melting furnace 6. Supplying. As auxiliary fuels, kerosene or heavy oil as the liquid fuel f and propane gas or natural gas as the gaseous fuel g are supplied from different systems.
[0023]
The temperature of the pyrolysis gas flowing through the pyrolysis gas channel 5 is measured by a temperature measuring device 12 including a thermocouple, and a measurement signal is input to the control device 13. When the temperature of the pyrolysis gas measured by the temperature measuring device 12 exceeds the softening temperature of the ash, the liquid fuel f (kerosene) is supplied. When the temperature of the pyrolysis gas is equal to or lower than the softening temperature of the ash, the gas fuel g (Propane gas). In this system, since the softening temperature of the ash in the garbage was about 1000 ° C., the supply control of the liquid fuel f (kerosene) and the gaseous fuel g (propane gas) was performed at a boundary of 1000 ° C.
[0024]
As described above, the refuse is supplied to the gasification furnace 3, where water is evaporated in the fluidized bed, and is thermally decomposed on the surface of the fluidized bed and the empty tower to generate gas and char. The air supplied to the gasification furnace 3 is only the fluidized air a, but since the inside of the furnace is kept at a negative pressure in order to prevent the gas from leaking out of the furnace, it is a dust supply system and a fluid medium. The air leaks into the gasification furnace 3 from a sand circulation system or the like. For this reason, a region having a high oxygen concentration is locally formed in the gasification furnace 3, and the pyrolysis gas and oxygen react to form a high-temperature region. When a liquid fuel f (kerosene) or a gaseous fuel g (propane gas) having a higher calorie than the pyrolysis gas is introduced into the gasifier 3, the temperature increases further by reacting with oxygen. Is eroded.
[0025]
In this respect, in this embodiment, the liquid as auxiliary fuel is supplied to the pyrolysis gas flow path 5 connecting the gasification furnace 3 and the melting furnace 6 where the pyrolysis reaction is completed and the oxygen concentration becomes almost zero or extremely low. Since the fuel f (kerosene) and the gaseous fuel g (propane gas) are supplied, a local high-temperature region is not formed in the gasification furnace 3, and melting of the refractory material can be avoided.
[0026]
Further, in the pyrolysis gas flow path 5, tar is generated when the temperature of the pyrolysis gas is low, and conversely, when the temperature is too high and becomes equal to or higher than the softening temperature of the ash, the ash adheres and the flow path is closed. There's a problem. In the fluidized-bed gasification furnace 3, the temperature of the bed is controlled to about 600 ° C. in order to stably fluidize the bed and thermally decompose the refuse. The bed temperature is controlled by adjusting the flow rate and temperature of the fluidized air a. However, since the amount of leaked air cannot be controlled at a constant value, if the bed temperature changes, the pyrolysis gas flow path will be adjusted accordingly. The temperature of the pyrolysis gas at 5 also changes.
[0027]
If the amount of fluidized air is increased when the amount of waste supplied or the quality of waste is changed, the bed temperature will temporarily increase, and the temperature of the pyrolysis gas will increase accordingly, and may exceed the softening temperature of ash. is there.
[0028]
For this reason, in the present invention, temperature control becomes possible by selectively using gaseous fuel and liquid fuel according to the temperature of the pyrolysis gas in the pyrolysis gas channel, and the blockage of the pyrolysis gas channel can be avoided. That is, when the pyrolysis gas temperature is lower than the ash softening temperature, gaseous fuel is supplied, and when the pyrolysis gas temperature is higher than the ash softening temperature, liquid fuel is supplied. This is because, when the liquid fuel is supplied, heat is absorbed at the time of evaporation, so that the temperature of the pyrolysis gas can be reduced. In this embodiment, kerosene which is a liquid fuel is supplied when the temperature of the pyrolysis gas in the pyrolysis gas flow path exceeds 1000 ° C., and propane which is a gaseous fuel is supplied at a temperature lower than 1000 ° C. Therefore, continuous operation was possible for a long period without blocking the pyrolysis gas flow path.
[0029]
If the length of the pyrolysis gas channel cannot be sufficiently secured, it is necessary to evaporate the liquid fuel in a short period of time. Therefore, it is better to supply the liquid fuel with a particle diameter of about 100 μm or less using a micronization device. .
[0030]
In addition, an auxiliary fuel was injected into a line for supplying combustion air to the melting furnace. However, since the air temperature was low, the liquid fuel flowed into the melting furnace without evaporating, and the temperature of the melting furnace outlet became high. Therefore, it is not preferable to supply fuel to a system having a relatively low temperature, such as a combustion air supply line flowing into the melting furnace. Further, when the gaseous fuel is supplied to the combustion air supply line, the gaseous fuel is brought into a combustion state depending on the condition, and the temperature of the air supply line abnormally rises.
[0031]
In the present embodiment, the total heat input to the melting furnace can be maintained constant even when any auxiliary fuel is used, so that the temperature of the melting furnace can always be kept at the melting temperature of ash, and stable melting can be performed. . The type of the melting furnace is not limited to the revolving type. In addition, when solid fuel such as coal is injected as auxiliary fuel, solid fuel such as coal has more fixed carbon content than char of garbage. I couldn't climb.
[0032]
A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, an oxygen concentration meter 14 is arranged at the upper part of the gasification furnace 3 or near the outlet, and confirms that the oxygen concentration is low, ie, about 2% or less, and assists the low oxygen concentration region. It supplies fuel. Since the amount of oxygen in the upper part of the gasification furnace 3 or in the vicinity of the outlet was smaller than the supply amount of the auxiliary fuel, heat was generated slightly, but there was almost no increase in the temperature, and therefore no melting damage of the refractory material was observed.
[0033]
A third embodiment of the present invention will be described with reference to FIG. This embodiment is applied to a pyrolysis gasification / melting furnace in which a rotary kiln type gasification furnace 15 and a swirling type melting furnace 6 are combined. Similarly, in the case of this embodiment, the liquid fuel f or the gaseous fuel g, which is an auxiliary fuel, is supplied to the pyrolysis gas flow path 5 connecting the gasification furnace 15 and the melting furnace 6, thereby enabling stable operation.
[0034]
【The invention's effect】
The present invention has the above-described configuration, and enables stable operation of the plant, and can avoid erosion of the refractory material in the gasification furnace, the melting furnace, and the pyrolysis gas flow path connecting the two. In addition, it has features that the blockage of the pyrolysis gas channel can be avoided, the amount of auxiliary fuel used can be minimized, and the cost of auxiliary fuel can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a pyrolysis gasification and melting system according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a pyrolysis gasification and melting system according to a second embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a pyrolysis gasification and melting system according to a third embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a conventional pyrolysis gasification and melting system.
[Explanation of symbols]
1: feed hopper, 2: dust supply device, 3: fluidized bed gasifier, 4: diffuser pipe, 5: pyrolysis gas flow path, 6: melting furnace, 7: secondary combustion chamber, 8: waste heat boiler , 9: temperature reducing device, 10: dust collecting device, 11: chimney, 12: temperature measuring device, 13: control device, 14: oxygen concentration meter, 15: rotary kiln type gasification furnace, a: fluidized air, b : Combustion air, c: slag, d: fly ash, f: liquid fuel, g: gaseous fuel

Claims (5)

Pyrolysis of general garbage and industrial waste in a pyrolysis gasifier, pyrolysis gas and char generated in the pyrolysis gasifier are burned in a melting furnace, and a high temperature field is obtained to melt the ash in the char. Thermal decomposition gasification and melting system
A pyrolysis gasification / melting furnace connected to the pyrolysis gasification furnace and a melting furnace and an auxiliary fuel supply system for supplying an auxiliary fuel to a pyrolysis gas flow path through which the pyrolysis gas and the char flow. system. Pyrolysis of general garbage and industrial waste in a pyrolysis gasifier, pyrolysis gas and char generated in the pyrolysis gasifier are burned in a melting furnace, and a high temperature field is obtained to melt the ash in the char. Thermal decomposition gasification and melting system
A pyrolysis gasification and melting system, wherein an auxiliary fuel supply system for supplying auxiliary fuel to a low oxygen concentration region near an upper portion or an outlet of the pyrolysis gasification furnace is provided. 3. The pyrolysis gasification and melting system according to claim 1, wherein the auxiliary fuel is a liquid fuel or a gaseous fuel. The pyrolysis gasification and melting system according to claim 3, wherein the pyrolysis gas flowing through the pyrolysis gas channel or the upper portion or the vicinity of the outlet of the pyrolysis gasification furnace exceeds the softening temperature of ash. And supplying a gaseous fuel when the pyrolysis gas is at or below the softening temperature of ash. 5. The pyrolysis gasification and melting system according to claim 3, wherein the liquid fuel is supplied to the pyrolysis gas flow path or the upper portion of the pyrolysis gasification furnace or in the vicinity of an outlet portion in a state of being atomized. Characterized pyrolysis gasification melting system.

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